With rapid development of the mobile Internet, explosive growth of a service volume continuously imposes a new demand on a mobile communications network, so that various new technologies emerge endlessly, such as an orthogonal frequency division multiplexing (OFDM) technology, a multi-antenna Multiple Input Multiple Output (MIMO) technology, a relay technology, a carrier aggregation (CA) technology, and a coordinated multi-point (CoMP) transmission technology. A common point of these new technologies lies in continuously pursuing improvement of spectral efficiency and a capacity of the mobile communications network.
From a theoretical analysis, a core of improving the spectral efficiency of the mobile communications network is to improve a signal to interference plus noise ratio. For example, this purpose may be achieved by using a technology such as interference coordination or power control. For improving the capacity of the mobile communications network, a relatively intuitive method is increasing an available resource of the mobile communications network. For example, direct improvement of the capacity of the mobile communications network can be achieved by increasing available bandwidth of the mobile communications network. With development of technologies, system bandwidth of the mobile communications network is also continuously improved. However, due to scarcity of a wireless spectrum resource, severe shortage of the spectrum resource has increasingly become a bottleneck of development of the wireless communications industry.
Based on the foregoing situation, in an existing situation of severe shortage of the spectrum resource, how to fully develop and use the limited spectrum resource and improve the spectral efficiency has become one of hot topics currently researched in the communications industry. A multi-antenna technology is widely favored because the multi-antenna technology can improve transmission efficiency without a need of increasing bandwidth. A principle of the technology lies in increasing a quantity of transmit antennas per unit physical area, so that a multiplexing degree of a time-frequency resource can be improved by fully using a channel characteristic without a need of increasing the bandwidth, thereby greatly improving the spectral efficiency. Specifically, after the multi-antenna technology is used, if enough differences of spatial sub-channels formed between antenna arrays of a transmit end and a receive end can be ensured, that different data flows are transmitted on different sub-channels can be implemented, so as to provide an additional spatial dimension besides a time domain and a frequency domain so that multiple users can share a same time, frequency, or code domain resource, thereby efficiently improving the spectral efficiency and the capacity. In the prior art, a heterogeneous network (HetNet), a distributed antenna system (DAS), a virtual multi-sector, an MIMO technology, and the like may be all considered as technologies that are based on the foregoing principle.
Currently, in the foregoing various prior arts in which the spectral efficiency is improved by increasing the quantity of antennas per unit area, there more or less exist defects such as a need of an additional site backhaul resource, impact on a coverage relationship between sectors, and a need of additional standardization support.